1. Field of the Invention
The present invention relates to ink jet printers, and, more particularly, to a method to improve the sealing of an ink jet printhead purge mechanism to an ink jet printhead.
2. Description of the Related Art
A typical ink jet printer includes a reciprocating carriage, also known as a carrier, carrying at least one ink jet printhead. The printhead includes a nozzle plate having a plurality of ink jet nozzles. Associated with each nozzle is an actuator, such as an electric heater or piezoelectric device, that when electrically energized causes ink to be ejected from the respective ink jet nozzle. As a sheet of print media is transported in an indexed manner under the printhead, the printhead is scanned in a reciprocating manner across the width of an image area on the sheet of print media. At least a portion of the scan path of the reciprocating printhead defines a print zone. A platen is provided opposite to the printhead for contacting the non-printed side of the print media and, in part, defines the distance between the printhead and the sheet of print media. The actuators associated with the plurality of ink jet nozzles are selectively energized to form an image on the sheet of print media in the image area.
In order to maintain satisfactory printing quality on a continuous basis, printhead maintenance is performed. Typically, a maintenance or cleaning station is provided for cleaning nozzles and capping the nozzle plates to form an air seal around the nozzles to prevent ink from drying in the nozzles. The maintenance station includes at least one wiper, and one cup-shaped printhead cap for each printhead. Briefly, a wiping sequence commences with the printhead over the media feed path and the top of the wiper below the media feed path. The wiper is raised until it extends into the path of the printhead surface containing the nozzles, and the printhead is moved to engage the wiper. Thus, accumulated ink and other foreign matter are wiped from the printhead as the printhead moves past the wiper. In a typical capping operation, the printhead is moved over the printhead cap and the cap is raised into contact with the printhead in an attempt to form an air tight seal around the region in which the nozzles are located.
In addition to wiping and capping the printhead nozzles, some ink jet printers include a purge mechanism that performs a vacuum purging procedure by applying a vacuum to the printhead nozzle plate during a maintenance operation to remove obstructions from the plurality of nozzles and the region adjacent thereto on the nozzle plate. Such a purge mechanism typically includes an elastomeric purge cap for covering the printhead nozzles, a vacuum pump for establishing a negative pressure, and a hose coupling the purge cap to the vacuum pump. For example, in some ink jet printers such a vacuum purging procedure is necessary to eliminate micro bubbles from the nozzles and the areas adjacent to the printhead nozzles. The micro bubbles are generated primarily by mechanical shock such as, for example, that resulting from the installation of an ink tank or printhead cartridge on the printer. Secondary sources of obstructive bubbles include air bubbles formed during ink de-gasification and air ingested through the nozzles caused by the re-forming of an ink meniscus following ink ejection from the nozzles during normal printing. Also, the purging operation is used to remove soft plugs and contamination from inside the ink jet nozzles and the area surrounding the nozzles on the nozzle plate during a maintenance cycle.
The effectiveness of the vacuum purging procedure depends to a large extent on the ability to establish and maintain an airtight seal around the printhead nozzles during the vacuum purging procedure. However, in practice it has proven to be difficult to obtain a repeatable, airtight seal around an ink jet nozzle region in order to efficiently and effectively pull a vacuum on the printhead to purge the ink jet nozzles of the printhead.
What is needed in the art is a method to improve the sealing of an ink jet printhead purge mechanism to an ink jet printhead.
The present invention provides a method of improving a sealing between a purge mechanism and a printhead.
In one form of the invention, the method includes the steps of providing the purge cap with a perimetrical sealing lip; and exercising the perimetrical sealing lip of the purge cap against a sealing surface of the printhead. The step of exercising is effected by generating a repetitive relative movement between the sealing surface of the printhead and the perimetrical sealing lip of the purge cap.
In another form of the invention, the method includes the steps of engaging the printhead with a purge cap; moving the printhead in a first direction away from the purge cap while maintaining contact between the printhead and the purge cap; moving the printhead bi-directionally in a reciprocating fashion while maintaining contact between the printhead and the purge cap; and moving the printhead in a second direction toward the purge cap.
In still another form thereof, the present invention provides a method of sealing a purge mechanism to a printhead surface of a printhead, including the steps of engaging the printhead surface with a purge cap; vertically raising the printhead while maintaining contact between the printhead surface and the purge cap; horizontally moving the printhead bi-directionally in a reciprocating fashion while maintaining contact between the printhead surface and the purge cap; and vertically lowering the printhead.
In still another form thereof, the present invention provides a method of improving a sealing between a purge cap of a purge mechanism and a printhead having a printhead surface, including the steps of engaging the printhead surface with the purge cap; decreasing a force exerted between the purge cap and the printhead surface while maintaining contact between the printhead surface and the purge cap; moving at least one of the printhead and the purge cap bi-directionally in a reciprocating fashion while maintaining contact between the printhead surface and the purge cap; and increasing the force exerted between the purge cap and the printhead surface.
An advantage of the present invention is that the sealing between a purge mechanism and a printhead is improved while utilizing existing printer hardware technology.
Another advantage is that the sealing between a purge mechanism and a printhead is improved without replacing any printer hardware components.